There is no evidence the Buddha himself spoke any sutta, apart from suttas that can be verified by meditation to accurately diagnose & end suffering. Therefore, we cannot know if the Buddha accepted the existence of Gods or what the Gods exactly were or meant to the Buddha. For example, in the suttas, Iti 106 says the Buddha said parents are the gods of their children; therefore gods in this context is obviously not supernatural.
It appears "Maghava" refers to "Sakka" in the Pali suttas, where eventually Sakka becomes a disciple of the Buddha. The following suttas are mere examples:
MN 37 - Sakka inquiring about Buddha's Dhamma then being warned by Buddha's chief disciple for being heedless in respect to sensual pleasures. Here, Sakka lives in a palace with many female nymphs.
SN 11.4, where Sakka is called "Maghavā" (bhayā nu maghavā sakka) when questioned by an asura about how to respond to & manage ordinary people.
DN 16 where Sakka expresses Noble or enlightened understanding to the Buddha's passing away: "Transient are all compounded things, Subject to arise and vanish; Having come into existence they pass away; Good is the peace when they forever cease.".
While each of the above may simply be religious propaganda written in religious scriptures (to propagate the Buddha is superior to Indra, Brahma & other Vedic & Hindu gods), each of the above shows Sakka is not eternal, not omniscient nor omnipotent. In fact, MN 37 & SN 11.4 give the impression Sakka is the leader of the rich & powerful, such as an Emperor of Rome, Genghis Khan, Suleiman the Magnificent or Lord Rothschild.
As for "heedfulness", this may not include the higher teachings of Buddhism such as not-self (anatta) that lead to Nibbana. For example, the word "heedfulness" or "carefulness" is found many times in the Jewish & Christian Bible. SN 11.4 shows how Sakka won the debate among the different gods by having heedfulness in relation to being patient. This does not show he was close to Nibbana. It only shows he had morality & was thus only heedful in respect to maintaining his patience & virtue.
Matali
‘When face to face with Vepacitti, is it, Maghava, from fear or
weakness, that you endure him so patiently, listening to his harsh
words?’
Sakka:
‘It is neither through fear nor weakness that I am patient with
Vepacitti. How can a wise person like me engage in combat with a
fool?’
Of goals that culminate in one’s own good
None is found better than patience.
One who repays an angry man with anger Thereby makes things worse for
himself. Not repaying an angry man with anger, One wins a battle hard
to win.
‘He practises for the welfare of both, His own and the other’s, When,
knowing that his foe is angry, He mindfully maintains his peace.
‘He achieves the cure of both— His own and the other’s.’
